February 20, 2003Carnegie Symposum1 X-Ray Studies of Nucleosynthesis and Abundances in Supernova Remnants John P. Hughes Rutgers University

February 20, 2003Carnegie Symposum2 Why X-rays? Ly  lines of all species from C (0.368 keV) to Zn (9.3 keV) Ly  lines of all species from C (0.368 keV) to Zn (9.3 keV) kT ~ 10 6 K to 10 8 K from shocks in ejecta and CSM/ISM kT ~ 10 6 K to 10 8 K from shocks in ejecta and CSM/ISM Si Fe S Ar Ca W49BASCA

February 20, 2003Carnegie Symposum3 X-ray Emission/Atomic Processes Continuum emission – thermal bremsstrahlung: Line emission: Abundance of element Z Ionization fraction of ion i

February 20, 2003Carnegie Symposum4 Abundance Determination Issues Thermodynamic State Thermodynamic State –Nonequilibrium Ionization (NEI) (n e t~10 5 cm -3 yr) –T, n evolution with time/radius (e.g., Sedov) –Other effects:  Heating/cooling in pure element ejecta  T e /T p  Nonthermal particles (rates and excitation) Absolute abundances (e.g., Si/H, O/H, Fe/H) Absolute abundances (e.g., Si/H, O/H, Fe/H) –Rely on assumption of H/He-dominated continuum Relative abundances (e.g., Mg/Si, O/Fe) Relative abundances (e.g., Mg/Si, O/Fe) –OK, if species have the same spatial distribution

February 20, 2003Carnegie Symposum5 Ejecta Mass Determination Issues Volume estimation Volume estimation Clumping (reduces actual mass) Clumping (reduces actual mass) Distance (M~D 5/2 ) Distance (M~D 5/2 ) Source of electrons Source of electrons –Measure EM = n e n I V –Solar abundance: n e ~ n H ~ n Fe / ~ 25000n Fe –Pure Fe: n e ~ 20n Fe –Inferred M pure Fe /M solar ~ 35

February 20, 2003Carnegie Symposum6 Where do we find ejecta? Optical: SNRs with high velocity oxygen-rich features Optical: SNRs with high velocity oxygen-rich features Galactic: Cas A, G , Puppis A Galactic: Cas A, G , Puppis A LMC/SMC: N132D, E , E LMC/SMC: N132D, E , E Other: an unresolved SNR in NGC 4449 Other: an unresolved SNR in NGC 4449 Remnants of historical SNe Remnants of historical SNe e.g., SN1006, SN1572 (Tycho), SN1604 (Kepler) e.g., SN1006, SN1572 (Tycho), SN1604 (Kepler) Based on [Fe II] in absorption; X-ray spectra Based on [Fe II] in absorption; X-ray spectra Ejecta-dominated SNRs Ejecta-dominated SNRs e.g., W49B, G , G , G e.g., W49B, G , G , G Based on X-ray spectra (mostly ASCA) Based on X-ray spectra (mostly ASCA) Nearly all remnants up to ages of at least ~10,000 yrs!!! Nearly all remnants up to ages of at least ~10,000 yrs!!! N49, N63A, DEM71, N49B, and E N49, N63A, DEM71, N49B, and E Based on Chandra spectro-imaging Based on Chandra spectro-imaging

February 20, 2003Carnegie Symposum7 Core Collapse Supernovae SN II, SN Ib/c (Zwicky & Baade 1934) SN II, SN Ib/c (Zwicky & Baade 1934) –Massive stars that explode with (SN II) or w/out (SN Ib/c) their H envelopes –Photodisintegration of Fe, plus electron capture on nuclei, remove central P support –Core collapses, leading to NS or BH –Core stiffens, rebounds and drives an outward moving shock –Neutrinos or jets needed to produce explosion –Mean Rate ~ 1.3 SNU

February 20, 2003Carnegie Symposum8 Nucleosynthesis in CC SNe Hydrostatic nucleosynthesis Hydrostatic nucleosynthesis –During hydrostatic evolution of star –Builds up shells rich in H, He, C, O, and Si –Amount of C, O, Ne, Mg ejected varies strongly with progenitor mass Explosive nucleosynthesis Explosive nucleosynthesis –Some mechanism drives a shock wave with erg through the Fe-core –Burning front T’s of ~10 9 K cause explosive O- and Si- burning –Only affects the central parts of the star – outer layers retain their pre-SN composition

February 20, 2003Carnegie Symposum9 Explosive Nucleosynthesis Process T (10 9 K) Main Products Explosive complete Si-burning 5.0 “Fe”, He Explosive incomplete Si-burning 4.0 Si, S, Fe, Ar, Ca Explosive O-burning 3.3 O, Si, S, Ar, Ca Explosive Ne/C-burning 1.2 O, Mg, Si, Ne

February 20, 2003Carnegie Symposum10 Overturning Our View of Cas A Hughes, Rakowski, Burrows, and Slane 2000, ApJL, 528, L109.

February 20, 2003Carnegie Symposum11 Cas A - Doppler Imaging by XMM Similar velocity structures in different lines Similar velocity structures in different lines –SE knots blueshifted –N knots redshifted –Tight correlation between Si and S velocities Fe Fe –Note velocity distribution in N –Extends to more positive velocities than Si or S Willingale et al 2002, A&A, 381, 1039

February 20, 2003Carnegie Symposum12 Cas A – 3D Ejecta Model Red: Si K  Green: S K  Blue: Fe K  Circle: Main shock “Plane of the sky” “Rotated” Fe-rich ejecta lies outside Si/S-rich ejecta

February 20, 2003Carnegie Symposum13 Oxygen-Rich SNR G Park et al 2001, ApJL, 564, L39

February 20, 2003Carnegie Symposum14 Oxygen-Rich SNR G Ejecta Rich in O, Ne, and Mg, some Si [O]/[Ne] < 1 No Si-rich or Fe-rich ejecta

February 20, 2003Carnegie Symposum15 Oxygen-Rich SNR G Normal Composition, CSM Central bright bar – an axisymmetric stellar wind (Blondin et al 1996) Thin, circumferential filaments enclose ejecta-dominated material – red/blue supergiant wind boundary

February 20, 2003Carnegie Symposum16 Thermonuclear Supernovae SN Ia (Hoyle & Fowler 1960) SN Ia (Hoyle & Fowler 1960) –No hydrogen, a solar mass of 56 Ni, some intermediate mass elements (O, Mg, Si, S,…) –Subsonic burning (deflagration) of approx. one Chandrasekhar mass of degenerate C/O –C-O white dwarf accreting H/He-rich gas from a companion –No compact remnant –Mean rate ~ 0.3 SNU

February 20, 2003Carnegie Symposum17 Identifying Remnants of SN Ia Balmer-dominated SNRs (partially neutral ISM) Balmer-dominated SNRs (partially neutral ISM) Ejecta abundances (Si and Fe rich, poor in O and Ne) Ejecta abundances (Si and Fe rich, poor in O and Ne) Remnant structure (uniform ISM, “smoother” ejecta, little spectral variation) Remnant structure (uniform ISM, “smoother” ejecta, little spectral variation) Tycho E

February 20, 2003Carnegie Symposum18 SN Ia Spectra and Abundances W7: Nomoto et al 1984, Thielemann et al 1993 WDD1: Iwamoto et al 1999 NEI fit: Warren et al 2003  Comparison to models  O, Ne, Mg: relatively low  Si, S, Ar, Ca: consistent  Fe: very low (<0.1)  Other spectral results  Fe: co-spatial with Si, but hotter and lower n e t

February 20, 2003Carnegie Symposum19 ISM Abundances of the LMC Using SNRs as a probe of the ISM Using SNRs as a probe of the ISM 7 SNRs, ages from 2,000 yr to 20,000 yr 7 SNRs, ages from 2,000 yr to 20,000 yr Data from ASCA Data from ASCA Spectra calculated for evolutionary models (Sedov solution) Spectra calculated for evolutionary models (Sedov solution) –spatial variation –temporal variation

February 20, 2003Carnegie Symposum20 LMC SNRs: Integrated Abundances From fits to ASCA global X-ray spectra of 7 evolved LMC remnants Hughes, Hayashi, & Koyama 1998, ApJ, 505, 732 N49B DEM L71

February 20, 2003Carnegie Symposum21 LMC Metal Abundances HHK95: ASCA X-ray SNRs Duf84: UV/Optical spectra H II regions (Dufour 1984) RD92: F supergiants (Mg, Si, Fe) (Russell & Bessel 1989) H II regions, SNRs (O, Ne, S) (Russell & Dopita 1990)SpeciesHHK98Duf84RD92O8.21(7)8.43(8)8.35(6) Ne7.55(8)7.64(10)7.61(5) Mg7.08(7) (13) Si7.04(8) ~7.8 S6.77(13)6.85(11)6.70(9) Fe7.01(11) 7.23(14)

February 20, 2003Carnegie Symposum22 DEM L71 Middle-aged SNR Middle-aged SNR –36” (8.7 pc) in radius –4,000 yrs old Rims: LMC composition Rims: LMC composition Core: [Fe]/[O] > 5 times solar Core: [Fe]/[O] > 5 times solar Ejecta mass: 1.5 M sun Ejecta mass: 1.5 M sun Hughes, Ghavamian, Rakowski, & Slane 2003, ApJ, 582, L95 SN Ia ejecta

February 20, 2003Carnegie Symposum23 N49B Middle-aged SNR Middle-aged SNR –80” (19 pc) in radius – ,000 yrs old Bright and faint rims Bright and faint rims –LMC composition –ISM density varies by x10 Ejecta Ejecta –Revealed by equivalent-width maps –Mg & Si rich, no strong O or Ne Park, Hughes, Slane, Burrows, Garmire, & Nousek 2003, ApJ, submitted.

February 20, 2003Carnegie Symposum24 SNR Middle-aged SNR Middle-aged SNR –87” (25 pc) in radius –>10,000 yrs old (?) Circular rim Circular rim –SMC composition Central bright region Central bright region –O, Ne, Mg, Si-rich ejecta –No Fe enhancement Park, et al 2003, ApJ, in prep.

February 20, 2003Carnegie Symposum25 Summary Core Collapse SNe Core Collapse SNe –Cas A  X-ray ejecta dominated by Si, S, and Fe –explosive nucleosynthesis  Extensive mixing and overturning of ejecta layers –G  X-ray ejecta dominated by O, Ne, and Mg (no Fe)  Ambient medium strongly modified by progenitor  Contains “normal” young pulsar and its wind nebula Highly Structured Ejecta/Environment

February 20, 2003Carnegie Symposum26 Summary Thermonuclear SNe (Tycho, E ) Thermonuclear SNe (Tycho, E ) –X-ray ejecta dominated by Si, S, and Fe –Stratification (most of the Fe core unshocked) –Fe: higher kT, lower n e t – due to:  evolution (ejecta density profile)  radioactivity –Ejecta relatively smooth and symmetric  only factor of 2 intensity variations  little spectral variation  few (one or two) clumps of Fe-rich ejecta

February 20, 2003Carnegie Symposum27 Summary Evolved LMC SNRs Evolved LMC SNRs –Global X-ray abundances consistent with optical/UV values –Individual SNRs show obvious signs of ejecta  DEM L71: 4,000 yrs, Si and Fe-rich SN Ia ejecta  N49B: 5,000-10,000 yrs, Mg and Si-rich ejecta  E : 10,000+ yrs, O, Ne, and Mg-rich ejecta Issues for nucleosynthesis models Issues for nucleosynthesis models –O/Ne ratio < 1 (G ) –O,Ne/Mg << 1 (N49B)

February 20, 2003Carnegie Symposum28 THE END

February 20, 2003Carnegie Symposum29 SN Ia Spectra and Abundances

February 20, 2003Carnegie Symposum30 Properties of DEM L71 Ejecta Outer rim: lowered abundances, ~0.2 solar (LMC ISM) Outer rim: lowered abundances, ~0.2 solar (LMC ISM) Core: enhanced Fe abundance, [Fe]/[O] > 5 times solar (ejecta) Core: enhanced Fe abundance, [Fe]/[O] > 5 times solar (ejecta) Thick elliptical shell, 32” by 40” across (3.9 pc by 4.8 pc) Thick elliptical shell, 32” by 40” across (3.9 pc by 4.8 pc) Dynamical mass estimate Dynamical mass estimate r’ ~ 3.0 M ej = 1.1 M ch (n/0.5 cm -3 ) Wang & Chevalier 2001 EM mass estimate EM mass estimate EM ~ n e n Fe V M Fe < 2 M sun Main error: source of electrons Main error: source of electrons Fe-rich, low mass SN Ia

February 20, 2003Carnegie Symposum31 N63A Middle-aged SNR Middle-aged SNR –34” (8.2 pc) in radius – yrs old –2 nd brightest LMC SNR “Crescent”-shaped features “Crescent”-shaped features –Similar to features in Vela –Clumps of high speed ejecta –Not ejecta dominated Triangular hole Triangular hole –X-ray absorption –Approx. 450 solar mass cloud –On near side No PSR or PWN No PSR or PWN – L X < 4x10 34 erg s -1 Warren, Hughes, & Slane, ApJ, in press (20 Jan 2003)